Carburizing apparatus



July 15, 1941. R. H. CRAMER 2,249,199 I CARBURI ZING APPARATUS? Filed Sept. 25, 1939 2 Sheets-Sheet i Fzq4 3o INVENTOR;

RAYMOND CRA/V'k,

BY v

H /S 17-70 12 NEX July 15, 1941..

R. H. cRAMER I 2,249,199

CARBURIZ ING APPARATUS Filed Sept. 23, 1939 2 Sheets-Sheet 2 INVENTCR I RAYMOND cRAMi/e,

us ATTORNEY Patented July 15, 1941 CARBURIZING APPARATUS Raymond H. Cramer, Newark, N. J., assignor to General Motors Corporation, Detroit, Mich, a 'cbrpdration of Delaware Application September 23, 1939, Serial No. 296.280

13 Claims. v(c1. 263-47) This invention relates to carburizing apparatus and comprises all of the features and aspects of novelty herein disclosed. An object of the invention is to provide improved apparatus for carburizing. Another object is to provide improved apparatus for handling relatively small articles to be heat treated, especially in a continuous tray type of gas carburizing furnace. Another object is to provide apparatus for traversing the articles to be carburized through a carburizing furnace and agitating the articles during such traverse to insure thorough and intimate exposure to the carburizing medium and thereby obtain uniform case depth. Another object is to provide a heat treating receptacle and a tray so constitute-d that sliding of the tray will rotate and traverse the receptacle through a heat chamber.

To these ends and also to improve generally upon devices of this character, the invention consists in the various matters hereinafter described and claimed. In its broader aspects, the invention is not necessarily limited to the specific constructions selected for illustrative purposes in the accompanying drawings in which Fig. 1 is a side view partly in section of a rotary receptacle in position on a sliding tray.

Fig. 2 is a cross sectional View of the receptacle on line 22 of Fig. 1.

Fig. 3 is a plan view of the improved tray.

Fig. 4 is a right hand end view of the receptacle and tray showing their relation to other similar parts on the furnace rails.

Fig. 5 is a sectional view partly in side elevation of a modified receptacle.

Fig; 6 is an end view of Fig. 5.

Fig. '7 is a section on line 1--1 of Fig. 5.

Fig. 8 is a sectional view partly in side elevation of another modification.

Fig. 9 is a sectional view of a rack and a front view of the central portion of a receptacle having a gear,

Fig. 10 is a section at right angles to Fig. 9.

Figs. 11 and 12 are views similar to Fig. 9 with the gear and rack differently located.

According to one embodiment, the article container comprises a perforated basket or drum having a series of bars I0 in circular arrangement with four bars [2 of increased depth arranged at points 90 apart and projecting radially into the container. Spaces l4 between the bars form slots or perforations to admit carburizing gas or other heating medium. The bars are welded to a series of hoops or rings is some of which act as tires. One end of the drum preferably has a permanent cover comprising a slotted disc I8 welded to a ring or flange 20, the latter being secured by welding 2| within the bars Ill and in rabbets of the bars 12. The material is preferably cold rolled alloy. The other cover 22 is similarly slotted and is detachably held in place by a long rod 24 which passes through both covers and is threaded to receive nuts 26. The ends of the rod are smooth to form trunnions 28 to co-operate with a skeleton push tray as the hoops or tires l6 roll along the usual longitudinal rails 30 in the furnace. The cross sectional outline of the heat chamber of the furnace which is preferably a continuous tray type gas carburizing furnace is indicated by the broken line 36.

Each tray comprises a pair of side bars 32 connected by end bars 34 to form a substantially rectangular skeleton tray. The side bars are also connected by cross bars 36 which project downwardly to form guide rails loosely embracing two are of particular benefit in. the usual furnace muflle. where the furnacerails are interrupted by valves. They prevent the tray from catching in the gap and they prevent the basket or drum from dropping any substantial distance into the The side bars are provided with pads 50 and the pads of adjacent trays engage one another as indicated in Fig. 4 'as' the trays are pushed through the furnace. Each tray pushes on the preceding one and advances its basket or drum by pushing on the trunnions 28. Since the drum projects through the bottomless tray and rests on the rails while being so pushed, it is compelled to rotate. Due to this rotation and to the extra depth of bars I2 the-contents of the drums are thoroughly agitated and come in intimate contact with the carburizing gases which are free to enter the perforations or slots in the drums and their covers. If desired, the slotted extensions 42 or the trunnions 28 or both can be omitted in V which case the lugs 46 of the tray will engage the tires 16 and advance the drum along the rails. In either case the bottomless tray carries none of the load and can be comparatively light. Figs. 5, 6 and 7 illustrate .an alternative 'c0nstruction of the basket or drum wherein a series of four bars are welded to the interior of cast circular sections 52 each of which is slotted and has an offset projection 54 overlying the adjacent section, some of the projections forming tires to roll on the furnace rails 30. One end of the drum comprises a slotted disc 56 permanently attached as by welding and having a projecting trunnion 58. The other end of the drum has a removable cover 60 similarly slotted and having a similar trunnion. This cover is slightly dished to enter the adjacent section 52 and to abut against the ends of the bars 5|. The cover has an overhanging flange 62 provided with inwardly projecting lugs 64 adapted to pass through slots; '65 between arcuate projections 66 on the adjacent section 52. When the cover is turned, the lugs 64 wedge behind the projections 66 and lock the cover. The trunnions 58 are intended to fit the open slots 44 in the trays of Fig. 4 but can be omitted.

Fig. 8 indicates another construction of the basket or drum. A slotted cylinder made from sheet alloy to resist heat and corrosion is welded to a series of bars 12, and a plurality of hoops or rings 14 are welded on the cylinder to form tires to roll on the rails 30. One end of the drum comprises a slotted disc 16 welded on and having a trunnion 18. The other end of the drum has a removable cover 80 having a similar trunnion. The cover 80 comprises a slotted disc welded to a ring 82 having bayonet slots 84 to engage lugs 86 on the drum. While Fig. 7 is drawn as a section of Fig. 5, it also constitutes a similar sectional view of Fig. 8.

Instead of relying on the traction of the tires on the rails to rotate the drum, the middle of the drum, as indicated in Figs. 9 and 10, can be provided with a gear 9|] which replaces the middle tire, the gear engaging a rack 92 fixed to the bottom of the carburizing chamber between overhanging lugs 94 which replace the middle rail. When the drum is pushed along by the tray, the gearing will provide positive means to rotate the drum.

According to Fig. 1d, a gear 96 is fixed to the drum between adjacent tires l6 to engage a rack 98 fixed to the bottom of the carburizing chamber between adjacent rails 30.

According to Fig. 12, a gear IUD is fixed to the drum beyond the endmost tire IE to engage a rack I 02 fastened to the bottom of the carburizing chamber beyond the endmost rail 30.

In operation the articles to be carburized or otherwise treated are placed in the slotted drums or baskets and each basket laid on a skeleton tray. The usual pusher mechanism slides the trays along the furnace rails, each tray engaging and pushing the preceding one. The tires I6 of the basket or drum of Fig. 1 rest on the furnace rails and, as the baskets are pushed by the trays, the baskets roll on the rails. Thus the baskets travel bodily through the furnace while being given a rotary movement. This rotary movement agitates the articles so that the carburizing gas has intimate contact therewith, thereby insuring uniform case depth. The apparatus can be used for heat treating other than carburizing. The receptacles of Figs. 5 and 8 are alternative constructions for the receptacle of Fig. 1. When the receptacles will roll properly without them, the trunnions can be omitted or the slotted projections on the ends of the trays, or both. When a positive rotation not depending on friction is needed, the gear and rack can be used. The perforated containers are well adapted to hold small articles which could not be readily stacked and conveyed on sliding trays and the rotation insures agitation and even penetration of the gas. When a receptacle is taken from the furnace, its contents can be emptied into the quenching medium after removal of the detachable cover but, if desired, the entire receptacle and contents can be quenched as a whole because the quenching medium will have access to the contents through the same slots which previously admitted the carburizing gases.

I claim:

1. In apparatus of the character indicated, a heat chamber having rails, a skeleton tray slidable on the rails, and a rotary container within the tray and adapted to roll along the rails; substantially as described.

2. In apparatus of the character indicated, a heat chamber having rails, a push tray slidable on the rails and having side bars, and a rotary container between the side bars and resting on the rails to roll thereon when the tray is pushed; substantially as described.

3. In apparatus of the character indicated, a heat chamber having rails, a rotary container in the chamber and having openings to admit the heated medium, and means including a push tray slidable on the rails for causing the container to progress bodily through the chamber while turning on its axis; substantially as described.

4. In apparatus of the character indicated, a heat chamber having rails, a rotary container resting on the rails and having trunnions, and a push tray slidable on the rails and engaging the trunnions to cause the container to roll upon the rails; substantially as described.

5. In apparatus of the character indicated, a heat chamber having rails, a rotary container resting on the rails and having trunnions, and a push tray slidable on the rails and having end members engaging the trunni-ons; substantially as described.

6. In apparatus of the character indicated, a heat chamber having rails, a series of push trays engaging one another and slidable on the rails, and a rotary container projecting through the bottom of each tray and engaging the rails; substantially as described.

7. In apparatus of the character indicated, a heat chamber having rails, a tray having side bars slidable on the rails supporting lugs projecting towards one another from the side bars and resting on the rails, there being a gap between the projecting lugs to expose the rails, and a container resting on the'rails in the gap; substantially as described.

8. In apparatus of the character indicated, a heat chamber having rails, a tray having side bars slidable on the rails, supporting lugs projecting from the side bars and having a gap therebetween, and a rotary container between the side bars and projecting into said gap to engage the rails; substantially as described.

9. In apparatus of the character indicated, a

heat chamber having rails, a tray having side bars slidable on the rails, guiding cross bars connecting the side bars and arranged alongside of the rails,'supporting lugs projecting towards one another from the side bars and resting on the rails, and a container resting on the rails in the gap between the supporting lugs; substantially as described.

10. In apparatus of the character indicated, a heat chamber having rails, a tray having side bars slidable on the rails, end bars connecting the side bars, the end bars having upwardly open slots, and a removable container having projecting members extending into the slots; substantially as described.

11. In apparatus of the character indicated, a heat chamber having rails, a tray having side bars slidable on the rails, end bars connecting the side bars and having upwardly open slots, and a rotary container having trunnions in said slots; substantially as described.

12. In apparatus of the character indicated, a rotary article container for heat treating comprising longitudinal bars spaced apart in a cirrotary container for heat treating comprising longitudinal bars arranged in a circular series and spaced apart to form openings, some of said bars projecting radially inwards farther than the others, and rings secured around the bars and forming tires; substantially as described.

RAYMOND H. CRAMER.

cular series to form a hollow cylinder having substantially V 

